Method for manufacturing crimped solvent-spun cellulose fibre of controlled quality

Abstract

Crimped fibres of solvent-spun cellulose are made and checked for damage in a method in which: i) cellulose is dissolved in an amine oxide solvent to form a hot cellulose solution, ii) the hot cellulose solution is extruded through a die assembly to form a tow of continuous filaments, iii) the tow is passed through a water bath to leach out the amine oxide iv) the tow is crimped by passing through a stuffer box in which it is compressed to apply crimp, v) dry steam being injected into the stuffer box during the crimping process, and vi) the crimped tow leaving the stuffer box is passed through detection means in which vii) a beam is projected across the path of travel of the tow and is received by receiving means on the opposite side of the tow, the receiving means being calibrated to initiate a signal if obscurement of the beam by the tow varies beyond a predetermined amount.

We claim: 
     
       1. A method for the production of staple cellulose fibre which comprises dissolving cellulose in an amine oxide solvent to form a hot cellulose solution, extruding the hot solution through a die assembly to form a multi-filamentary tow of continuous filaments, passing the tow of continuous filaments through a water bath to leach out the amine oxide, crimping the leached tow in a stuffer box while simultaneously injecting dry steam into the stuffer box, withdrawing the crimped tow from the stuffer box and moving it along a predetermined path while applying tension to the tow in the range of 0.55 pounds/kilotex to 1.88 pounds/kilotex, projecting a light beam across the crimped tow as it is moved along said path under tension in said range, measuring the degree by which the beam is obscured by the tow and generating a signal when the beam is obscured by more than a predetermined amount, and then passing the tow downstream of the beam to a cutter and cutting the tow with the cutter to form a staple fibre. 
     
     
       2. The method claimed in claim 1 wherein the tow is dried after being passed through the water bath and before being crimped. 
     
     
       3. The method claimed in claim 1 wherein the signal is an audible signal. 
     
     
       4. The method claimed in claim 1 in which the degree by which the beam is obscured by the tow is monitored by a microprocessor. 
     
     
       5. A method according to claim 1, in which the amine oxide solvent is a tertiary amine N-oxide.